Rotary regenerator matrix seal with clearance control means



F 1968 A. N. ADDIE ETAL 6 ROTARY REGENERATOR MATRIX SEAL WITH CLEARANCE CONTROL MEANS Filed June 12, 1967 3 Sheets-Sheet l 5g EA'TUR 52 5 fliezy/Yldddz BY Jodi Hart Feb. 6, 1968 A. N. ADDIE ETAL 3,367,405

ROTARY REGENERATOR MATRIX SEAL: WITH CLEARANCE CONTROL MEANS Filed June 12, 1967 3 Sheets-Sheet r:

IN VENTORS I 025mm (M1166 1 Jack Hzzari TORNEY Feb. 6, 1968 A. N. ADDIE ETAL 3,367,405

ROTARY REGENERATOR MATRIX SEAL WITH CLEARANCE CONTROL MEANS 5 Sheets-Sheet 5 Filed June 12, 1967 United States Patent Ofiflce ABSTRACT OF THE DISCLGSURE In a rotary regenerator in which the matrix includes labyrinth sealing strips movable with respect to the body of the matrix and held in tension, the sealing strips are provided with a follower to engage a guide or rubbing strip on the stationary seal bar in the regenerator with which the labyrinth strips cooperate. The guide and follower thus deflects the labyrinth strips to establish a definite location of the center point of the labyrinth strip as it passes through the seal, the end points of the labyrinth strip being located by their attachment to the matrix structure. Close control of seal clearance is thus provided. In the preferred form, the follower is a block fixed to two adjacent seal strips and overhanging into position to abut the adjacent blocks. Preferably, the sealing strips are slightly high at the center so that they may be deflected inward to conform to a straight seal bar.

This application is a continuation-in-part, as to divisible subject matter, of our application Ser. No. 484,219 for Regenerator Matrix, filed Sept. 1, 1965. It is related to our copending application Ser. No. 653,288, filed June 12, 1967, for Regenerator Matrix which is a continuation-in-part of Ser. No. 484,219, now abandoned.

Our invention is directed to improving the sealing in rotary regenerators. These are devices in which a matrix moves continuously between two passages, one containing a Warmer fluid and the other a cooler fluid, so that the matrix transfers heat from the warmer fluid to the cooler. Particularly in a regenerator for a gas turbine engine, there is a considerable difference of pressure between the two fluids and thus the problem of preventing excessive leakage of fluid from the higher pressure to the lower pressure where the matrix passes through the bulkhead which separates the two fluids.

Ordinarily, a labyrinth type seal is used involving sealing strips which project slightly from the face of the matrix and pass close to a stationary seal bar mounted on the bulkhead. Relative expansion of the parts, and particularly distortion of the matrix because of the temperature gradients existing during operation, make this sealing a problem of some difficulty. Prior approaches to maintaining the desired controlled gap betweeen the labyrinth seal strips and the fixed seal bar have involved such ideas as causing the seal bar to distort more or less conformably to the matrix, making the seal bar of segments which can shift relatively to follow the changing contour of the matrix, and providing labyrinth seal strips which do not deform along with the matrix. Our parent application Ser. No. 484,219 is directed to the last-mentioned approach.

In the invention of this application we have gone beyond the concept of making the labyrinth seal strips free from the matrix and causing them to maintain their own contour, by putting them in tension, and have added means for positively locating at least one point in the span of the labyrinth seal strip by rubbing contact with a portion of the sea-l bar. Specifically, in the preferred embodiments of this invention, the labyrinth strips bear follower means of hard metal at their mid-points and a hard metal guide means or rubbing shoe on the seal bar contacts the followers so as to deflect the mid-point of the labyrinth seal slightly, thus establishing a definite location of the center of the strip and preventing any variation in labyrinth seal gap due to friction between the labyrinth strips and the remainder of the matrix; also preventing any unwanted rubbing between the labyrinth strips and the body of the seal bar which might occur if the strips should project slightly too far from the matrix.

The invention is illustrated and described herein as applied to a regenerator which is the subject of the copending application of Albert N. Addie for Rotary Regenerator Ser. No. 644,860, filed June 9, 1967, but the principles of the invention are clearly applicable to various regenerators, including regenerators of the axial-flow or disk type as opposed to the drum type illustrated herein.

The principal objects of our invention are to improve the efficiency and reliability of rotary regenerators and of gas turbine engines incorporating them; to improve the sealing of rotary regenerators; to improve the life and durability of such regenerators, and to provide a regenerator structure which is more suited to the requirements of practice than those previously known.

The nature of our invention and the advantages thereof will be clear tov those skilled in the art from the succeeding detailed description of embodiments of the invention and the accompanying drawings thereof.

FIGURE 1 is a schematic illustration of a regenerator installation taken on a plane perpendicular to the axis of the matrix, with parts cutaway.

FIGURE 2 is a fragmentary sectional view on a plane generally correspodnig to that of FIGURE 1 illustrating the coaction of the matrix and the primary seal therefor.

FIGURE 3 is a sectional view taken on a plane containing the axis of the matrix as indicated by the line 33 in FIGURE 2.

FIGURE 4 is an exploded view of a portion of the matrix illustrated in FIGURE 3.

FIGURE 5 is a sectional view of a second and preferred form of regenerator matrix with parts cut away, the sec tion being taken approximately on a plane containing the axis of the matrix.

FIGURE 6 is an external view of the matrix taken on the plane indicated by the line 6-6 in FIGURE 5.

FIGURE 7 is a fragmentary sectional view of the same taken on the plane indicated by line 77 in FIGURE 5.

FIGURES 8, 9, and 10 are fragmentary sectional views taken on planes perpendicular to the matrix axis as indicated by the lines 8-8, 9 9, and 1010 in FIGURE 5.

FIGURE 11 is a fragmentary sectional view taken on the plane indicated by the line 11-11 in FIGURE 10. Thicknesses are exaggerated in FIGURES 8 to 11.

FIGURE 12 is an exploded view of the follower means of the preferred form of the invention.

Referring first to FIGURE 1, which illustrates in a general way the regenerator and its relation to a gas turbine engine, the engine includes a turbine 13 which drives a compressor 14 through a shaft 15 and also drives a power output shaft 17. It includes regenerator 18 which comprises a regenerator case or housing 19 and a drumshaped matrix 21 which rotates about a horizontal axis 22 perpendicular to the axis of the turbine. A bulkhead 23 and associated structure divides the interior of the regenerator case between a high pressure chamber 25 into which the compressor discharges and a low pressure chamber 26 into which the turbine discharges. Main support and seal assemblies 27 are mounted in the bulkhead at the places where the drum passes through the bulkhead as it is slowly rotated about the axis 22. Air from the compressor flows through the portion of the Patented Feb. 6, 1968:

3 matrix ahead of the bulkhead, through combustion apparatus (not illustrated), and through the turbine 18 to chamber 26 where it flows outward through the portion of the matrix rearward of the bulkhead to an exhaust stack 29.

Refer to FIGURES 2, 3, and 4 which illustrate a matrix structure which is one of the forms shown in our copending application Ser. No. 653,288, filed June 12, 1967, and in our. parent application Ser. No. 484,219. The matrix comprises two coaxial rims 30, each rim consisting primarily of an end ring 31. The rim also includes retainer rings 33 and 34. These rings are segmented, and will be described. The end rings are fixed together by a number of stiifeners 35 parallel to the matrix axis, which are bolted to the end rings. In the particular matrix described there are twenty-five such stiffeners. A considerable number of shim packs 3'7 are mounted between the end rings between each two adjacent stiffeners, fifteen in this example. These shim packs are made up of corrugated thin temperature-resistant sheet metal and are porous to gas flow radially of the matrix. Seal and spacer groups 38 are disposed between adjacent shim packs and between the shim packs and the stiffeners.

The elements of the seal and spacer groups are shown most clearly in FIGURE 4. These are a sheet metal spacer plate 39 to which are brazed or otherwise fixed rectangular sheet metal bosses 41 and a similar spacer plate 43 having bosses 44. When the matrix is assembled, the bosses 41 and 44 are in face to face abutment. A labyrinth seal element 45 is disposed between the abutting spacers. The seal element comprises a sealing strip 46 extending across the outer or cold face of the matrix, struts 47 extending toward the hot face of the matrix, and a segmented sealing strip 49 at the hot face of the matrix supported by the struts 47. The strip 46 lies between the radially outer edges of plates 39 and 43 and the 'bosses 43 together provide clearance for seal element 45 so that it is free of any pressure from the compacted shim packs in the matrix. Sealing strip 49 lies radially inward of the inner margins of plates 39 and 43, which separate adjacent shim packs to provide space for movement of sealing strips 49.

The spacers 39 and 43 include integral lugs 50 at their ends which are received in a circumferential recess 51 in the rim defined by the end ring 31 and the retainer ring 34. The shim packs are similarly located radially of the matrix by projections (not illustrated) at the ends of the shim packs which are received in the recess 51.

The seal elements 45 are retained by structure mounted on retainer segments 33 and 34. An arcuate strip 53 of I-beam section retained by the retainer segments33 and 34 is notched to receive tabs 54 extending from the ends of sealing strip 46. Rectangular holes 55 in tabs 54 are engaged by two rectangular keys 57 and 58 which are lodged between the retainer segments 33 and 34 and behind the flange 59 of the I-beam strip. Thus, to assemble the matrix the end rings 31 are fixed to the stifieners by bolts (not illustrated), the labyrinth seal elements 45 are disposed between the spacer plates 39 and 43, and the shim packs 37 are disposed between the seal and spacer groups 38. The tabs 54 are inserted into the slots in the strip 53 and the keys 57 and 58 are put in place. The retainer segments are then disposed on either side of the strip 53. The whole assembly is moved into place between the stifieners and the retainer segments 33 and 34 are held in place by bolts 61.,This structure is described in our parent application and our companion application Ser. No. 653,288, filed June 12, 1967, in greater detail, but the present description is sufficient for an understanding of the invention to which this application is directed.

FIGURES 1, 2, and 3 show to the extent necessary to explain the present invention the coaction between the matrix described above and the sealing and driving structure in the regenerator. The main support and seal assemblies 27 include a frame defined in part by an outer housing 62 and an inner housing 63. Support rollers 65 are mounted rotatably in the case 19 and disposed within the housing 63. Aligning rollers 66 are supported on the frame within the outer housing 62. These rollers engage the rim 30 of the matrix to locate it and drive it and to locate the fixed seal bars of a primary seal with respect to the matrix. These seal bars are an outer or cold side seal bar 67 and an inner or hot side seal bar 69. The details of the primary seal including means by which the seal bars are supported are described in the above'mentioned copending application Ser. No. 644,860, filed June 9, 1967, of Albert N. Addie. They are believed to be immaterial to the present invention.

The seal barspresent cylindrical surfaces which are maintained a small distance from the radially inner and outer surfaces of the matrix by aligning means including the rollers 65 and 66. The seal bars extend across the face of the matrix and, in the particular embodiment, the cold side seal bars are spaced one hundredth of an inch from the sealing strips 46 of the matrix and the hot side seal bars three hundredths of an inch from the matrix sealing strips 48. These clearances relate to a large matrix two feet wide and might be less in a small device. Since the ends of the seal bars 67 and 69 which are located with definite clearance from the matrix rim and the ends of seal strips 46 are located by the rim, the clearance at that point is easy to control.

The means for controlling clearance at at least one intermediate point in the span of the sealing strip is the subject of this application. This clearance control includes guide means on the cold side seal bar and follower means on the sealing strips 46 which engage the guide means and sweep over the surface of the guide means as the sealing strip moves through the primary seal. In the embodiment of FIGURES 3 and 4, the follower means is provided by three small rectangular blocks 70 of tungsten carbide brazed to the middle point of cold side sealing strip 46. These blocks project approximately .010 inch beyond the radially outer surface of the sealing strip. The guide means is provided by an adjustable shoe 71 mounted on the cold side seal bar 67. As shown, shoe 71 is held to the cold side housing 62 by studs 73 and a pair of wedges 74 may be moved for accurate adjustment of the alignment of shoe 71 with the face of seal bar 67. By providing the guide and follower it is possible to locate both the ends and the center of the sealing strip 46 at the desired .010 inch clearance from the cylindrical seal bar, the seal bar being deflected slightly inward each time it passes through the seal by engagement with the guide 71, which has ramp surfaces 75 and 76 at its ends. This positive location of the cold side sealing strip 46 is transmitted through the struts 47 to the hot side segmented sealing strip 48. This structure has been shown by tests to perform well the purpose for which it was intended, but it has not proved entirely satisfactory in service endurance. One reason for this is the differential thermal expansion of the martensitic stainless labyrinth sealing strip 46 and the tungsten carbide follower blocks 70 brazed to it, which caused undesirable residual stresses and stress concentration. The stress was concentrated in the sealing strip as the follower engaged the guide. Altogether, there was an undesirable degree of fatiguing of the labyrinth strips at the point adjacent to the tungsten carbide blocks.

FIGURES 5 through 11 show an improved matrix structure which overcomes the disadvantages of the earlier form just referred to and has considerable other advantages. The difference between the two lies primarily in the seal and spacer groups. The spacers are similar in principle but have different structure. The seal plate itself may have the same structure except for the difference in the arrangement of followers. In the preferred form, the follower is in the form of a composite block mechanically fixed to two adjacent sealing plates to constitute a dual labyrinth assembly. The improved structure could be used with the rim and tensioning structures shown in FIG- URES 3 and 4 but, as illustrated, it is incorporated in a different matrix structure which will only be described briefly to the extent necessary to understand our invention, since other aspects of the matrix are the inventions of others.

Referring to the drawings, the matrix comprises a rim 80 including an end ring 81, an outer retainer segment 83, and an inner retainer segment 84. These retainer segments extend between stifleners 85 which rigidly connect the two rims. Fifteen shim packs 87 extend across the matrix between each two adjacent stiffeners, these shim packs being each made up of a considerable number of corrugated thin sheet metal plates with an uncorrugated plate at each face of the pack. Seal and spacer groups 90 each comprising two labyrinth sealing elements and the accompanying spacers are mounted at each side of each stiffener. Additional seal and spacer groups 91 are mounted between the remaining shim packs. The two types of seal and spacer groups are essentially identical, but a small difference will later be pointed out. Referring to FIGURES to 11, each seal and spacer group includes two sealing plates or labyrinth seal elements 92 each of which comprises a cold side sealing strip 93 extending across the outer surface of the matrix, a number of struts 94 (eight as illustrated), and a segmented hot side sealing strip 96, each segment of which is mounted on the end of a strut 94. The ends of the sealing strips 93 are provided with openings 101 through which are threaded the keys 102 and 103 which lie behind the slotted shoulder 104 of I-beam section mounting strip 105. The outer flange 107 of this strip is held by the retainer segments 83 and 84. The retainer segments 83 and 84 are fixed together by machine screws (not illustrated) and two flanges (FIGURE 5) of the sealing strip 84 straddle a radially outwardly extending flange 108 on the rim. The assembly is then retained in place on the rim by latches 109 at each end of the assembly which are received in recesses 110 in the inner wall of the end ring 81.

Before sealing plates 92 are connected to the rims, the seal and spacer groups and shim packs are associated with them.

Before proceeding to the interconnection of the sealing plates into the dual labyrinth assemblies 112 illustrated in FIGURES 5, 6, and 12, it may be best to consider briefly the structure of the spacer with reference to FIG- URES 5 and 8 to 11. Note that thickness of the parts and clearances are exaggerated in FIGURES 8 to 11 for clarity. A seal and spacer group such as 91 comprises the sealing plate 92 and two spacers 114. Each spacer is made up primarily of two plates spot-welded together, an outer plate 116 and an inner plate 117. The outer edge of the outer plate extends across the matrix substantially in the plane of the shim pack and slightly below the edge of the cold side sealing strip 93. It includes a tongue 118 (FIGURE 5) which fits into an annular recess in the rim defined by the end ring 81 and the inner retainer segment 84. Its lower margin terminates substantially short of the inner margin of the matrix as shown at 119. Slots 121 extend outwardly from the radially inner margin of the outer plate in alignment with the struts 94. The inner plates 117 define generally rectangular portions 122 which lie within the rectangular openings 123 in the sealing plate 92. The inner plates 117 also include bridge portions 124 which extend from each rectangular portion 117 to the next and are offset into the plane of outer plates 116 in the slots 121 so as to constitute a continuation of the outer plates and thus provide clearance for struts 94 of the sealing plate. The plates 116 and 117 are spot-welded together to constitute a single spacer. Spacing tab 125 (FIGURE 8) is spot-welded to each of the tongues 118 to assure proper spacing of the tongues so that the spacers cannot close in on the strut 94 adjacent the rim. It will thus be seenthat, as in the previous form,

6 the sealing plates 92 are free to move radially of the matrix or, more generally, from face to face of the matrix, to accommodate to the fixed seal bars and to maintain the desired edge contours notwithstanding thermal distortion of the remainder of the matrix.

Considering now the structure of the dual labyrinth assembly 112 with particular reference to FIGURES 5, 6, and 12, it should be remembered that each adjacent pair of sealing plates 92 or, more specifically, the midpoints of the cold side sealing strips 93, are coupled together to form the dual labyrinth assembly. The structure by which they are mechanically coupled together includes a follower or 131. These followers include means to engage the guide means 71 on the cold side seal bar. The followers are blocks made up of several parts which are mechanically coupled by pins to the sealing strips. The followers 130 and 131 are substantially identical, the difference being that the followers 131 disposed immediately adjacent the stilfeners are dimensionally different. Referring to FIGURE 12, two tongues 133 project away from the sealing edge of the cold side seal bar at its mid-point. A generally rectangular block 135 having a slot 136 at its inner edge is disposed between the two sealing strips, the walls of slot 136 being aligned with the walls of the slots 134 in the sealing strips. The follower assembly also includes a saddle 139 which has a central portion 141 dimensioned to fit within the slots 134 and 136 and two flanges or end blocks 143 integral with the saddle. The sealing strips 93 are thus disposed between the block 135 and the flanges 143. The whole assembly is held together by two pins or dowels 144 pressed through holes 145 in the sealing strips 93, 146 in the saddle, and 147 in the filler block. The pins may be secured by staking the ends of holes 146. A baflle or filler piece 149 is spotwelded to the underside of saddle 141 so as to close off the portion of slot 134 which is not closed by the saddle 141. Three wear strips 151 are brazed to the surface of block 135. These are of hard material such as tungsten carbide so as to resist wear in rubbing over the guide 71.

The follower arrangement just described has numerous advantages. It presents a relatively large area of the wear strips to bear against the guide, reducing unit pressure and therefore wear. This, taken in connection with the attachment of the follower to two sealing strips, greatly increases the torsional stability of the structure; in other words, there is no longer any significant tendency to twist the sealing strip as a result of friction between the guide and the follower. Because of the mechanical attachment of the follower assembly to the sealing strips as opposed to the brazing of FIGURES 3 and 4, stress concentration and residual stresses between the follower and sealing strips are eliminated or minimized. Moreover, the follower if worn can be removed from the sealing strips without damaging the sealing strips.

The flanges 143 of the adjacent follower assemblies 130 or 131 are normally out of contact but can engage as a result of the slight circumferential deflections of the sealing strips caused by reversals of pressure. When the sealing strips are traveling from one pressure zone to the other, they are biased by the pressure differential against the spacer toward the low pressure side of the sealing strip. The bias is, of course, in one direction around the matrix at one main seal and in the other direction at the other main seal. It may be noted that the stiffener has recesses 152 on opposite faces to receive the end or flange of follower assembly 131. This end is shorter than the other end of this follower assembly and the ends of the follower assemblies 130.

The margin of the shim pack is cut away to provide a channel with slight clearance from the followers 130 and 131.

Certain values and dimensions of a particular matrix according to our invention may be of interest. This matrix is approximately two feet wide. The thermal distortion is such that, with the matrix shim pack surface cylindrical when cold, the radius at the rim is approximately 0.180 inch greater than that at the middle of the matrix under normal operating conditions. Apart from the overall thermal expansion of the matrix drum there is a differential expansion of about 0.180 inch in the radius between the ends and the center. The cold side seal strips 93 are originally crowned to the extent that the radius of the matrix over the seals is 0.030 to 0.040 inch greater at the center than at the rims. The edge of the cold side seal strips is parallel to the hot side sealing strips. The seal bars 67 and 69 and the guide 71 define cylinders concentrio with the matrix axis. It is not necessary to provide a warped surface to conform to the warping of the body of the matrix. With this structure as, the followers 70 or 130 engage the guide 71, the cold side seal strips are deflected 0.030 to 0.040 of an inch so that the edge of the cold side sealing strip is rectilinear as it passes in sealing relation to the seal bar. This forced straightening of the cold side sealing strips is transmitted through the struts to the hot side sealing strips, which are accordingly maintained in an essentially straight condition, subject only to the slight deformation of the segments due to the temperature gradient across the hot side sealing strip.

The centers of the sealing plates 92 are thus worked in and out a matter of 0.03 or 0.04 inch with respect to the spacers at each pass through the seals. This slight reciprocation is beneficial in eliminating any possibility of sticking of the seal strips, with resulting possible contact of the sealing strips with the seal bars or excess clearance, decreasing the effectiveness of the seal. In the example referred to the sealing strips 93 are approximately onehalf inch wide and 0.020 inch thick and are under approximately 500 pounds tension so that there is ample strengthening force exerted upon them, but not excessive force. Because of the relatively small deflection, the radial contact force between the guide and follower is relatively small.

The scope of the invention is not to be considered as limited by the detailed description of embodiments of the invention, since many variations embodying the principles of the invention may be devised by the exercise of skill in the art.

We claim:

1. An annular rotary regenerator matrix having two faces and coaxial rims extending from face to face bounding the matrix, comprising heat-transfer material of a structure pervious to fluid flow from face to face mounted between the rims, labyrinth sealing strips distributed circumferentially of the matrix extending from rim to rim across a face of the matrix and projecting from the surface of the heat transfer material, and sealing strip mounting means effective to locate the ends of the strips relative to the rims, to free the sealing strips from constraint by the heat transfer material, and to put the sealing strips in tension, in combination with follower means mounted on the sealing strips intermediate the rims adapted to cooperate with guide means on a cooperating seal member effective to determine a path of movement of the sealing strips to control the clearance between the sealing strips and a said seal member.

2. A matrix as recited in claim 1 in which the edges of the sealing strips are crowned.

3. A matrix as recited in claim 1 in which the portion of the sealing strip at which the follower means is mounted extends outward from the matrix beyond a straight line joining the ends of the sealing strip, and the. edge of the sealing strip converges toward the said straight line toward the ends of the sealing strip.

4. A matrix as recited in claim 1 in which the follower means is mechanically attached to the sealing strip.

5. A matrix as recited in claim 1 in which the matrix includes sealing strips on the other face of the matrix,

and including means interconnecting the sealing strips at opposite faces so that deflection of the sealing 8 strips on the said one face effects deflection of the sealing strips on the said other face.

6. A matrix as recited in claim 5 in which the sealing edges of the sealing strips on the said one face are convex.

7. A matrix as recited in claim 1 in which each follower means comprises a block fixed to two adjacent sealing strips extending with clearance over the matrix between the said sealing strips.

8. A matrix as recited in claim 7 in which the blocks overhang the sealing strips into juxtaposition to adjacent blocks.

9. A matrix as defined in claim 1 in which the sealing strips and follower means include the following:

means on each sealing strip defining a slot in the strip at the edge remote from the sealing edge,

a block extending between the confronting faces of a pair of adjacent sealing strips,

a saddle including a central portion underlying the block and extending through the said slots and including two end flanges disposed on the opposite sides of the said two sealing strips from the block,

and attaching means passing through the flanges, sealing strips, and block.

10. A rotary regenerator comprising, in combination:

a case including a bulkhead dividing the case into two chambers, an annular matrix mounted for rotation within the case and extending through one or more openings in the bulkhead between the said chambers, the matrix having two faces and coaxial rims extending from face to face bounding the matrix, and having heat-transfer material of a structure pervious to fluid flow from face to face mounted between the rims, and sealing means adapted to minimize leakage between the matrix and bulkhead from one chamber to the other;

the sealing means comprising, in combination,

labyrinth sealing strips distributed circumferentially of the matrix extending from rim to rim across a face of the matrix and projecting from the surface of the heat transfer material,

sealing strip mounting means effective to locate the ends of the strips relative to the rims, to free the sealing strips from constraint by the heat transfer material, and to put the scaling strips in tension,

a stationary seal member mounted on the case adjacent said opening extending across the matrix face in position to cooperate with said sealing strips to provide a labyrinth seal,

follower means mounted on the sealing strips intermediate the rims,

and guide means on the seal member in position to engage the follower means so that the follower means are guided thereby as the sealing strips move past the seal member,

the configuration of the guide means and follower means being such as to determine a path of movement of the sealing strips to control the clearance between the sealing strips and seal member.

11. A regenerator as recited in claim 10 in which the edges of the .sealing strips are crowned.

12. A regenerator as recited in claim 10 in which the portion of the sealing strip at which the follower means is mounted extends outward from the matrix beyond a straight line joining the ends of the sealing strip, and the edge of the sealing strip converges toward the said straight line toward the ends of the sealin g strip.

13. A regenerator as recited in claim 10 in which the matrix includes sealing strips on the other face of the matrix,

and including means interconnecting the sealing strips at opposite faces so that deflection of the sealing strips on the said one face effects deflection of the sealing strips on the said other face.

14. A regenerator as recited in claim 13 in which the 9 10 sealing edges of the sealing strips on the said one face follower means mounted on the sealing strips interare convex. mediate the rims,

15. A rotary regenerator comprising, in combination: a stationary seal member mounted on the case adjacent a case including a bulkhead dividing the case into two said opening extending across the matrix face in chambers, an annular matrix mounted for rotation position to cooperate with said sealing strips to prowithin the case and extending through one or more vide alabyrinth seal, openings in the bulkhead between the said chambers, and guide means on the seal member in position to the matrix having two faces and coaxial rims extend engage the follower means so that the follower ing from face to face bounding the matrix, and havmeans are guided thereby as the sealing strips move ing heat-transfer material of a structure pervious to past the seal member, fluid flow from face to face mounted between the the configuration of the guide means and follower rims, and sealing means adapted to minimize leakmeans being such as to deflect the sealing strips with age between the matrix and bulkhead from one respect to the spacer means as the sealing strips pass chamber to the other; the stationary seal member. the sealing means comprising, in combination, labyrinth sealing strips distributed circumferentially of References Cited the matrix extending from rim to rim across a face UNITED STATES PATENTS gt the matrix and pro ecting from the surface of the 3,181,603 5/1965 Bubniak et a1 165 9 eat transfer material, sealing strip mountin" means effective to locate the ends 3186479 6/1965 Mondt -10 3,216,487 11/1965 Gallagher 1659 of the strips relative to the rims and put the sealing stripsintension, EDWARD 1'. MICHAEL, Primary Examiner. spacer means effective to free the seallng strips from constraint by the heat transfer material, DAVIS, Assistant Examiner- 

